System and method for controlled fuel blending in gas turbines

ABSTRACT

A system includes a gas turbine engine having a combustor, and a fuel blending system. The fuel blending system further includes a first fuel supply configured to supply a first fuel, a second fuel supply configured to supply a second fuel, a first fuel circuit, a second fuel circuit, and a controller. The first fuel circuit may be configured to blend the first fuel and the second fuel to form a first to form a first fuel mixture. The second fuel circuit may be configured to blend the first fuel and the second fuel to form a second fuel mixture. The controller may be configured to regulate blending of the first fuel mixture and the second fuel mixture based on a measured operating parameter of the combustor.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to gas turbine systems, andmore particularly, to a system for blending fuel in a gas turbinesystem.

Gas turbine systems typically include at least one gas turbine enginehaving a compressor, a combustor, and a turbine. The combustor may haveone or more combustion systems with fuel nozzles for receiving fuelgases. Certain fuel gases may not be, by themselves, suitable for use asa fuel source in combustion-driven equipment, such as in a gas turbinesystem. For example, certain fuel gases may be less available in largerquantities, or might be more costly to use. By further example, certainfuel gases may be abundantly found, but may not have, by themselves, thechemical composition suitable for efficient operation within the gasturbine system. Furthermore, certain fuel gases may result inundesirable exhaust emissions, such as nitrogen oxides (NOx), sulfuroxides (SOx), carbon monoxide (CO), carbon dioxide (CO2), and so forth.The emission levels may exceed thresholds, such as minimum emissioncompliance levels, for gas turbine systems.

BRIEF DESCRIPTION OF THE INVENTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In a first embodiment, a system includes a gas turbine engine having acombustor, and a fuel blending system. The fuel blending system furtherincludes a first fuel supply configured to supply a first fuel, a secondfuel supply configured to supply a second fuel, a first fuel circuit, asecond fuel circuit, and a controller. The first fuel circuit may beconfigured to blend the first fuel and the second fuel to form a firstto form a first fuel mixture. The second fuel circuit may be configuredto blend the first fuel and the second fuel to form a second fuelmixture. The controller may be configured to regulate blending of thefirst fuel mixture and the second fuel mixture based on a measuredoperating parameter of the combustor.

In a second embodiment, a system includes a fuel blending system havinga first fuel circuit, a second fuel circuit, and a controller. The firstfuel circuit may be configured to supply a first fuel mixture of a firstfuel and a second fuel to a primary fuel nozzle of a turbine combustor.The second fuel circuit may be configured to supply a second fuelmixture of the first fuel and the second fuel to a secondary fuel nozzleof the turbine combustor. The controller may be configured to regulate afirst blending ratio of the first fuel mixture and a second blendingratio of the second fuel mixture based on a measured operating parameterof the turbine combustor.

In a third embodiment, a method includes measuring an operatingparameter of a gas turbine combustor, where the operating parameter isused to regulate blending of a first fuel with a second fuel. The methodfurther includes blending the first fuel with a second fuel based on theoperating parameter to form a first fuel mixture having a first blendingratio. The method further includes blending the first fuel with thesecond fuel based on the operating parameter to form a second fuelmixture having a second blending ratio, where the first and secondblending ratios are different.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic of an embodiment of a gas turbine system having acompressor, a plurality of combustors, a turbine, and a plurality offuel nozzles;

FIG. 2 is a cross-sectional side view of an embodiment of one of theturbine combustors illustrated in FIG. 1, configured to receive fuelgases from a fuel blending system;

FIG. 3 is a schematic of an embodiment of the fuel blending system ofFIG. 2, where the fuel blending system includes a blending skid, aprocess gas supply, a natural gas supply, and a controller.

FIG. 4 is a flow diagram illustrating an embodiment of a method by whicha fuel blending system may blend a first fuel and a second fuel; and

FIG. 5 is a flow diagram illustrating an embodiment of a method by whicha fuel blending system may modify fuel blending based on an operatingparameter of the combustor.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

The disclosed embodiments are directed towards a fuel blending systemwhich may receive and blend a first fuel source with a second fuelsource to form a fuel mixture. The fuel blending system may thentransfer the fuel mixture to a fuel nozzle of combustion-drivenequipment, such as a combustor in a gas turbine system. In certainembodiments, the fuel blending system may receive and blend a naturalgas with one or more process gases (e.g., a blast furnace gas, a cokeoven gas, a refinery flue gas, or any synthetic gas generated as aresult of a refinery or chemical process) to form the fuel mixture. Inparticular, the fuel blending system may be configured to blend thenatural gas and the process gas based on a measured composition of thefirst fuel source (e.g., a measured composition of the process gas). Assuch, blending may be regulated, so that the use of certain fuel sourcesis optimized or maximized. For example, the fuel blending system maycontrol blending of the fuel mixture such that the amount of process gasis optimized or maximized when generating or creating the fuel mixtureof natural gas and process gas.

In yet other embodiments, after transferring the fuel mixture to thecombustor in the gas turbine system, the fuel blending system maymonitor the combustion dynamics of the combustor. For example, certainoperating parameters of the combustor, such as flame intensity,pressure, temperature, vibration, or the chemical composition of theburned fuel mixture, may be measured. By further example, the monitoredoperating parameters may include or identify variations, such aspulsations or oscillations, in pressure, temperature, flame intensity,and/or chemical compositions. The fuel blending system may be furtherconfigured to blend the fuel mixture based on one or more measuredoperating parameters, and thus may use fuel sources more efficiently andeffectively. For example, blending may be regulated so that only acertain amount of additional fuel is transferred to the combustor forcontinued combustor operation. Additionally, blending may be adjusted ina feedback control loop so that one or more operating parameters of thecombustor remain within combustion boundaries of the system. The fuelblending system may also control the blending of the fuel mixture, sothat a certain quantity of a particular fuel is used to create the fuelmixture. That is, as mentioned above, an amount of a particular fuel(e.g., a process gas) used in generating the fuel mixture may bemaximized or optimized based at least partially on feedback (e.g.,measured operating parameters) from the combustor. In addition, the fuelblending system may supply a particular blend of fuel that enables thecombustor to achieve desired low levels of emissions, such as NOxemissions, SOx emissions, CO emissions, and/or CO₂ emissions.

Turning now to the drawings, FIG. 1 illustrates a block diagram of anembodiment of a gas turbine system 10. The gas turbine system 10includes a compressor 12, turbine combustors 14, and a turbine 16. Theturbine combustors 14 includes fuel nozzles 18 which route a liquidfuel, a gas fuel (e.g., natural gas), and/or a blended fuel (e.g., amixture of natural gas and process gas) into the turbine combustors 14.For example, the process gas may include a blast furnace gas, a cokeoven gas, a refinery flue gas, a synthetic gas generated as a result ofa refinery or chemical process, or a combination thereof. As shown, eachturbine combustor 14 may have multiple fuel nozzles 18. Morespecifically, the turbine combustors 14 may each include primary fuelnozzles 20 and secondary fuel nozzles 22. As discussed in detail below,the primary fuel nozzles 20 and secondary fuel nozzles 22 receive fuelfor use within the turbine combustors 14. The turbine combustors 14ignite and combust an oxidant—fuel mixture (e.g., an air-fuel mixture),and then pass resulting hot pressurized combustion gasses 24 (e.g.,exhaust) into the turbine 16. Turbine blades within the turbine 16 arecoupled to a shaft 26 of the gas turbine system 10, which may also becoupled to several other components throughout the turbine system 10. Asthe combustion gases 24 flow against and between the turbine blades ofthe turbine 16, the turbine 16 is driven into rotation, which causes theshaft 26 to rotate. Eventually, the combustion gases 24 exit the turbinesystem 10 via an exhaust outlet 28. Further, in the illustratedembodiment, the shaft 26 is coupled to a load 30, which is powered viathe rotation of the shaft 26. The load 30 may be any suitable devicethat generates power via the rotational output of the turbine system 10,such as an electrical generator, a propeller of an airplane, or otherload.

The compressor 12 of the gas turbine system 10 includes compressorblades. The compressor blades within the compressor 12 are coupled tothe shaft 26, and will rotate as the shaft 26 is driven to rotate by theturbine 16, as discussed above. As the compressor blades rotate withinthe compressor 12, the compressor 12 compresses air (or any suitableoxidant) received from an air intake 32 to produce pressurized air 34.The pressurized air 34 is then fed into the fuel nozzles 18 of thecombustors 14. As mentioned above, the fuel nozzles 18 mix thepressurized air 34 and fuel to produce a suitable mixture ratio forcombustion, e.g., a combustion that causes the fuel to more completelyburn, so as not to waste fuel or cause excess emissions. In thefollowing discussion, reference may be made to an axial direction oraxis 42 (e.g., a longitudinal axis) of the combustor 14, a radialdirection or axis 44 of the combustor 14, and a circumferentialdirection or axis 46 of the combustor 14.

FIG. 2 is a cross-sectional side view of an embodiment of one of thecombustors 14 in the gas turbine system 10 of FIG. 1, where thecombustor 14 is configured to receive fuel from a fuel blending system50 (e.g., a multi-fuel supply system). As mentioned above, the combustor14 is operatively coupled to the compressor 12 and the turbine 16.Specifically, the combustor 14 combusts the pressurized air 34 from thecompressor 12 with fuel from the fuel blending system 50 and directs theresulting combustion gases 24 into the turbine 16. In the illustratedembodiment, the combustor 14 includes include a primary combustion zone52 and a secondary combustion zone 54 downstream from the primarycombustion zone 52. In other embodiments, the combustor 14 may have onlythe primary combustion zone 52 or a plurality of combustion zones (e.g.,two, three, four, five, or more combustion zones). The fuel nozzles 18route a liquid fuel, a gas fuel, and/or a blended fuel from the fuelblending system 50 into the primary and secondary combustion zones 52and 54. For example, the fuel may be natural gas, a process gas, and/ora mixture of natural gas and process gas. For example, the process gasmay include a blast furnace gas, a coke oven gas, a refinery flue gas,any synthetic gas generated as a result of a refinery or chemicalprocess, or a combination thereof. In certain embodiments, the fuelblending system 50 may be configured to send a different type of fuel,or a different mixture of fuel, to different fuel nozzles 18 of thecombustor 14. For example, in one embodiment, the fuel blending system50 may provide a first fuel mixture (e.g., having a first fuelcomposition) to the primary fuel nozzles 20, which are configured toroute the first fuel mixture to the primary combustion zone 52.Concurrently, the fuel blending system 50 may also provide a second fuelmixture (e.g., having a second fuel composition different from the firstfuel composition of the first fuel mixture) to the secondary fuelnozzles 22, which are configured to route the second fuel mixture to thesecondary combustion zone 54. For example, the first and second fuelmixtures may each be mixtures of natural gas and process gas, but thefirst and second fuel mixtures may have different blend ratios ofnatural gas to process gas. In this manner, each combustion zone (e.g.,the primary and secondary combustion zones 52 and 54) of the combustor14 may receive a different or unique fuel mixture from the fuel blendingsystem 50.

In the illustrated embodiment, the combustor 14 has an annulus 56configured to receive pressurized air from the compressor 12. Thepressurized air received by the annulus 56 from the compressor 12 isdirected towards a head end 58 of the turbine combustor, as shown byarrows 60. In certain embodiments, the annulus 56 of the combustor 14may be defined by a liner 62 (e.g., an inner wall) and a flow sleeve 64(e.g., an outer wall), where the flow sleeve 64 surrounds the liner 62(e.g., coaxially or concentrically). The head end 58 of the turbinecombustor 14 may have a cover plate 65 and an end plate 66, which may atleast partially support the primary fuel nozzles 20. In certainembodiments, the primary fuel nozzles 20 may combine the fuel receivedby the fuel blending system 50 with the pressurized air from thecompressor 12 to create an air/fuel mixture. The air/fuel mixture isthen combusted in the primary combustion zone 52 to produce combustiongases 68. While the illustrated embodiment shows fuel being supplied tothe primary fuel nozzles 20 by only the fuel blending system 50, otherembodiments of the combustor 14 may include multiple fuel supplies,and/or multiple fuel blending systems 50. Furthermore, in embodimentshaving multiple fuel supplies and/or multiple fuel blending systems 50,the fuel supplies may provide the same fuel types, or different fueltypes, to the primary fuel nozzles 20.

The combustion gases 68 created in the primary combustion zone 52 flowdownstream from the head end 58 of the combustor 14 to the tail end 70(e.g., a downstream end of a transition piece 69) of the combustor 14.As mentioned above, in certain embodiments, the combustor 14 may includethe secondary combustion zone 54 with secondary fuel nozzles 22. Thesecondary fuel nozzles 22 may inject additional fuel into the stream ofcombustion gases 68 for combustion in the secondary combustion zone 54,as indicated by arrows 71. The secondary fuel injection 71 may be angledupstream toward the head end 58, downstream toward the tail end 70, orgenerally crosswise (e.g., perpendicular) to the flow of gases 68. Incertain embodiments, the secondary fuel nozzles 22 may combine the fuelreceived by the fuel blending system 50 with the pressurized air fromthe annulus 56 (i.e., the pressurized air supplied by the compressor 12,as shown by arrows 60) to create an air/fuel mixture, which may beinjected 71 and combusted in the secondary combustion zone 54 to produceadditional combustion gases 68. In other embodiments, the secondary fuelnozzles 22 inject fuel and air separately into the stream of combustionproducts 68 for combustion in the secondary combustion zone 54. Whilethe illustrated embodiment shows fuel being supplied to the secondaryfuel nozzles 22 by only the fuel blending system 50, other embodimentsof the combustor 14 may include multiple fuel supplies, and/or multiplefuel blending systems 50. In embodiments having multiple fuel suppliesand/or multiple fuel blending systems 50, the fuel supplies may providethe same fuel type, or different fuel type, to the secondary fuelnozzles 22. After combustion in the secondary combustion zone 54, thecombustion gases 68 continue downstream, as indicated by arrow 72,toward the turbine 16.

In certain embodiments, the fuel blending system 50 may include ablending skid 74, at least one process gas supply 76 for supplying aprocess gas, a natural gas supply 78 for supplying a natural gas, and acontroller 80 with a processor 81 and a memory 82. The process gassupply 76 may be any type of process gas, such as, for example, a blastfurnace gas, a coke oven gas, a refinery flue gas, a synthetic gasgenerated as a result of a refinery or chemical process, or acombination thereof. Thus, the process gas supply 76 may include a firstprocess gas supply (e.g., a coke oven gas supply, a second process gassupply (e.g., a blast furnace gas supply), a third process gas supply,or any other number of process gas supplies. The blending skid 74regulates the blending of the process gas supply 76 (e.g., the coke ovengas, the blast furnace gas, or a combination of the two) with thenatural gas supply 78. In certain embodiments, the controller 80 of thefuel blending system 50 may control operations of the blending skid 74by regulating the blending of the process gas supply 76 with the naturalgas supply 78.

In one embodiment, the controller 80 may regulate blending based on ameasured composition of the process gas supply 76. For example, thecontroller 80 may determine the chemical composition of the process gassupply 76 and measure the concentration of process gas supply 76components, such as nitrogen, carbon dioxide, hydrogen sulfide, oxygen,and so forth. Based on measured concentrations of constituentcomponents, the controller 80 may adjust the blending of the natural gassupply 78 (e.g., natural gas) with the process gas supply 76 (e.g.,process gas) to maintain or regulate the concentrations of variouscomponents within desired operating boundaries of the combustor 14. Inanother embodiment, the controller 80 may regulate blending based on ameasured composition of the natural gas supply 78. For example, thecontroller 80 may determine the chemical composition of the natural gassupply 78 and measure the concentration of the natural gas supply 78components, such as nitrogen, carbon dioxide, hydrogen sulfide, oxygen,and so forth. Based on measured concentrations of the constituentcomponents, the controller 80 may adjust the blending of the natural gassupply 78 (e.g., natural gas) with the process gas supply 76 (e.g.,process gas) to maintain or regulate the concentrations of variouscomponents within desired operating boundaries of the combustor 14.

Furthermore, the controller 80 may regulate blending based on parametersset by an operating user's input, which may be stored in the memory 82of the controller 80. The memory 82 may further be used to store othermeasured values, such as operating parameters of the combustor 14, ormeasured concentrations of fuel gas components (e.g., components of thenatural gas or the process gas). In yet other embodiments, thecontroller 80 may be configured to regulate blending based on a measuredcomposition of the natural gas supply 78, the process gas supply 76, orbased on measured compositions of both the natural gas supply 78 and theprocess gas supply 76 (i.e., the blended mixture of the natural gassupply 78 and the process gas supply 76). For example, the controller 80may measure the concentration of natural gas supply 78 components suchas nitrogen, carbon dioxide, hydrogen sulfide, or oxygen.

In other embodiments, the controller 80 of the fuel blending system 50may control operations of the blending skid 74 based on combustor 14operating feedback. For example, the operating feedback may beparameters measured from within the primary and/or secondary combustionzones 52 and 54 or other areas of the combustor 14, such as the fuelnozzles 18 (e.g., primary and secondary fuel nozzles 20 and 22), exhaustsection 28, turbine 16, or any combination thereof. That is, theoperating dynamics of the combustor 14 may be quantified with variouscombustion dynamics parameters, and may be obtained with a plurality ofsensors 84.

The sensors 84 may be any suitable type of sensors, such as, forexample, a flame detector or an acoustic probe, and the sensors 84 maybe positioned in the primary and/or secondary combustion zones 52 and54. The flame detector may be configured to measure a combustiondynamics parameter, such as flame intensity of a flame within thecombustor 14, while the acoustic probe may be configured to measurefrequency or amplitude of a tone of the combustor 14. The sensors 84 mayalso be other types of sensors, such as, for example, optical sensors,mechanical sensors, pressure sensors, temperature sensors, vibrationsensors, or electrical sensors, which may be configured to measure otheruseful combustion dynamics operating parameters such temperature,pressure, and so forth. For example, the sensor feedback may be used toidentify pulsations or oscillations in pressure, temperature, flameintensity, light intensity, noise, emissions levels, or any combinationthereof. The sensors 84 may send measured data of the combustor 14operating parameters to the controller 80, which may then use themeasured data to further regulate the operation of the blending skid 74and the fuel blending system 50.

The memory 82 of the controller 80 may further store the measuredcombustor 14 operating parameters. In this manner, the controller 80 mayregulate a feedback control loop that may adjust the ratio of thenatural gas supply 78 (e.g., natural gas) to the process gas supply 76(e.g., process gas) within the fuel mixture based on combustor 14operating feedback from the primary and/or secondary combustion zones 52and 54 or other areas of the combustor 14.

FIG. 3 is a schematic of an embodiment of the fuel blending system 50 ofFIG. 2, where the fuel blending system 50 includes the blending skid 74,the process gas supply 76, the natural gas supply 78, and the controller80. As discussed in FIG. 2, the controller 80 may control operation ofthe blending skid 74, such that the blending skid 74 regulates theblending of the process gas supply 76 (e.g., a blast furnace gas, a cokeoven gas, a refinery flue gas, a synthetic gas generated as a result ofa refinery or chemical process, or a combination thereof.) with thenatural gas supply 78 (e.g., the natural gas). The controller 80 mayregulate the operation of the blending skid 74 based on a measuredcomponent composition of the process gas supply 76. In otherembodiments, the controller 80 may regulate the operation of theblending skid 74 based on a measured component composition of thenatural gas supply 78, the process gas supply 78, or measuredcompositions of both the process gas supply 76 and the natural gassupply 78 (i.e., the blended mixture of the process gas supply 76 andthe natural gas supply 78). Components of the gas supplies 76 and 78,such as nitrogen, carbon dioxide, hydrogen sulfide, or oxygen, may bemeasured with sensors 86, and the measured data may be sent to theprocessor 81 and/or memory 82 of the controller 84, or to anothercomponent of the controller 84.

The controller 80 may also regulate the operation of the blending skid74 based on combustor 14 operating feedback 88 (e.g., feedback from theprimary and/or secondary combustion zones 52 and 54). For example,combustor 14 operating feedback 88 may include measured data on variouscombustion dynamics parameters, such as, for example, flame intensity,frequency or amplitude of a tone, temperature, pressure, and so forth.Other combustion dynamics parameters that may be indentified includepulsations or oscillations in pressure, temperature, flame intensity,light intensity, noise, emissions levels, or any combination thereof.The combustion dynamics parameters measure the combustion dynamicswithin the primary and/or secondary combustion zones 52 and 54 or otherareas of the combustor 14, and may be based on the properties of thefuel being used within the combustion zones 52 and 54. In certainembodiments, it may be desirable to maintain combustion dynamicsparameters within certain operating boundaries so as to regulate theoperability or efficiency of the combustor 14, and/or to reduce hardwaredegradation within the gas turbine system 10. For example, theconcentration of certain constituents, such as nitrogen, carbon dioxide,hydrogen sulfide, oxygen, and so forth, may be maintained belowthreshold levels of the combustor 14. To this end, the controller 80 maybe used to regulate or operate a feedback control loop and regulate theblending operations of the blending skid 74, such that the combustiondynamics parameters remain within the operating boundaries of thecombustor 14.

As shown, the blending skid 74 of the fuel blending system 50 mayregulate the blending of the process gas supply 76 (e.g., e.g., a blastfurnace gas, a coke oven gas, a refinery flue gas, a synthetic gasgenerated as a result of a refinery or chemical process, or acombination thereof) with the natural gas supply 78 (e.g., the naturalgas) within one or more fuel circuits. In the illustrated embodiment,the blending skid 74 includes a first fuel circuit 90, a second fuelcircuit 92, and a third fuel circuit 94. In other embodiments, theblending skid 74 may have four, five, six or any suitable number of fuelcircuits. Each fuel circuit may transfer a fuel mixture of the naturalgas supply 78 and the process gas supply 76 to the fuel nozzles 18 ofthe combustor 14, to a transfer skid, or to another combustor 14. Forexample, the first fuel circuit 90 may transfer a first fuel mixture toone or more primary fuel nozzles 20, while the second fuel circuit 92may transfer a second fuel mixture to one or more secondary fuel nozzles22. In addition, the fuel blending system 50 may deliver a blended orunblended fuel to a transfer system 96 (e.g., a transfer skid or fueltransfer system). For example, in one embodiment, the third fuel circuit94 may transfer only the natural gas supply 78 to the transfer system96, and transfer of fuel from the natural gas supply 78 to the transfersystem 96 may be regulated using a gas transfer valve 98.

Moreover, a plurality of valves may enable the blending skid 74 to blenddifferent ratios of natural gas from the natural gas supply 78 relativeto process gas from the process gas supply 76 for different fuelcircuits of the blending skid 74. In certain embodiments, the controller80 may control the operation of the valves based on measured datareceived from the combustor 14 operating feedback 88, based on measuredcomponent compositions of the natural and/or process gas supplies 76 and78, and/or based on user input. The first fuel circuit 90 may have afirst fuel mixture with a first ratio of natural gas supply 78 (e.g.,natural gas) to process gas supply 76 (e.g., process gas). The firstfuel mixture may be formed when gas release valves 100 and 102 enablegas flow from the natural gas supply 78 and the process gas supply 76,respectively, into the blending skid 74. As shown, the blending skid 74further includes gas control valves 104 and 106. Gas control valve 104regulates the flow of natural gas from the natural gas supply 78 withinthe first fuel circuit 90, while gas control valve 106 regulates theflow of process gas from the process gas supply 76 within the first fuelcircuit 90. Together, the gas control valves 104 and 106 may create afirst blend ratio of the natural gas supply 78 (e.g. natural gas) to theprocess gas supply 76 (e.g., process gas). Similarly, the second fuelcircuit 90 may have a second fuel mixture with a second ratio of naturalgas supply 78 (e.g., natural gas) to process gas supply 76 (e.g.,process gas). The second fuel mixture may be formed when gas releasevalves 100 and 102 release natural gas from the natural gas supply 78and process gas from the process gas supply 76 into the blending skid74. Thereafter, gas control valves 108 and 110 regulate blending of thenatural gas and process gas within the second fuel circuit 90. Morespecifically, gas control valve 108 regulates the flow of natural gasfrom natural gas supply 78 within the second fuel circuit 92, while gascontrol valve 110 regulates the flow of process gas from the process gassupply 76 within the second fuel circuit 92. Together, the gas controlvalves 108 and 110 create a second blend ratio of the natural gas supply78 (e.g., natural gas) to the process gas supply 76 (e.g., process gas).As mentioned above, the first fuel circuit 90 may produce a first blendratio that is different from the second blend ratio in the second fuelcircuit 92. More specifically, the controller 80 may be able to formfuel mixtures with different blend ratios for each fuel circuit of thefuel blending system 50. Furthermore, each fuel circuit of the fuelblending system 50 may transfer fuel mixtures with different blendratios to the various fuel nozzles 18 of the combustor 14.

FIG. 4 is a flow diagram illustrating an embodiment of a process 112(e.g., a computer-implemented process) by which the fuel blending system50 may blend a first fuel (e.g., natural gas) and a second fuel (e.g., aprocess gas). The process 112 begins by setting a gas turbine mode ofthe gas turbine system 10 of FIG. 1 (block 114). In certain embodiments,the gas turbine system 10 may be set to a premixing mode, where fuel issupplied to both the primary fuel nozzles 20 and the secondary fuelnozzles 22. In other embodiments, other modes of operation for the gasturbine system 10 may be employed, such as a primary mode, secondarymode, a full load mode, a part load mode, a startup mode, a steady statemode, and so forth. Each mode of the gas turbine system 10 may use adifferent blend ratio of the first fuel to the second fuel, and mayadditionally provide a different blend ratio for each fuel nozzle of thecombustor. For example, the gas turbine engine system 10 may blend adifferent blend ratio of the first fuel to the second fuel in thepremixing mode than it would in a steady state mode, startup mode, etc.

In certain embodiments, after the gas turbine system 10 is set to a gasturbine mode, the controller 80 may measure a component composition of afirst fuel, such as, for example, process gas from the process gassupply 76 (block 116). As described in detail above, the controller 80may regulate the operation of the blending skid 74 of the fuel blendingsystem 50 based on a measured component composition of the process gasfrom the process gas supply 76 (e.g., a blast furnace gas, a coke ovengas, a refinery flue gas, a synthetic gas generated as a result of arefinery or chemical process, or a combination thereof.). For example,the sensors 86 (as shown in FIG. 3) may assess the chemical compositionof the process gas from process gas supply 76 by measuring theconcentration of components like nitrogen, carbon dioxide, hydrogensulfide, oxygen, and so forth. In other embodiments, the controller 80may regulate the operation of the blending skid 74 based on a measuredcomponent composition of the natural gas from the natural gas supply 78,or gases of both the process gas supply 76 and the natural gas supply78.

The process 112 may further include blending the first fuel with asecond fuel to form a first fuel mixture (block 118) and a second fuelmixture (block 120). For example, in certain embodiments, process gasfrom the process gas supply 76 may be blended with natural gas from thenatural gas supply 78 at a first ratio to form a first fuel mixturewithin a first fuel circuit 90 (block 118). Likewise, process gas fromthe process gas supply 76 may be blended with natural gas from thenatural gas supply 78 at a second ratio to form a second fuel mixturewithin a second fuel circuit 92 (block 120). Each fuel circuit of theblending skid 74 may have a different blend ratio of the natural gassupply 78 (e.g., natural gas) to the process gas supply 76 (e.g.,process gas). Thus, the first fuel mixture of the first fuel circuit 90may have a different blend ratio than the second fuel mixture of thesecond fuel circuit 92. In other embodiments, the first fuel mixture ofthe first fuel circuit 90 may have the same blend ratio as the secondfuel mixture of the second fuel circuit 92. In the illustratedembodiment, two fuel circuits are shown. Each fuel circuit has adifferent blend ratio. In other embodiments, three, four, five, or anyother number of fuel circuits with or without different blend ratios maybe given. Furthermore, based on the data received from the sensors 86,the controller 80 may adjust the ratio of the blend within a particularfuel circuit. For example, if the concentration of nitrogen within theprocess gas supply 76 is known or measured, then the controller 80 mayblend or adjust a fuel mixture within the first fuel circuit 90 that isoptimized to achieve certain operating parameters within the combustor14 (e.g., a desired amount of nitrogen within the combustion products68).

Last, the process 112 may include transferring the first fuel mixture toa first fuel nozzle (block 122), and the second fuel mixture to a secondfuel nozzle (block 124). For example, the first fuel circuit 90 may bedirected towards the primary fuel nozzles 20, while the second fuelcircuit 92 may be directed towards the secondary fuel nozzles 22. Assuch, the fuel nozzles 18 of the combustor 14 may each receive adifferent blend ratio of the natural gas supply 78 to the process gassupply 76. That is, the primary fuel nozzles 20 may receive the firstfuel mixture having a first blend ratio from the first fuel circuit 90,and the secondary fuel nozzles 22 may receive the second fuel mixturehaving a second fuel ratio (e.g., different from the first fuel ratio)from the second fuel circuit 92.

FIG. 5 is a flow diagram illustrating an embodiment of a process 126 bywhich the fuel blending system 50 may modify fuel blending based on anoperating parameter of the combustor 14. The process 126 begins bysetting a gas turbine mode of the gas turbine system 10 of FIG. 1 (block128). In certain embodiments, the gas turbine system 10 may be set to apremixing mode, where fuel is supplied to both the primary fuel nozzles20 and the secondary fuel nozzles 22. In other embodiments, other modesof operation for the gas turbine system 10 may be employed, such as aprimary mode, secondary mode, a full load mode, a part load mode, astartup mode, a steady state mode, and so forth. Each mode of the gasturbine system 10 may use a different blend ratio of the first fuel tothe second fuel, and may additionally provide a different blend ratiofor each fuel nozzle of the combustor. For example, the gas turbineengine system 10 may blend a different blend ratio of the first fuel tothe second fuel in the premixing mode than it would in a steady statemode, startup mode, etc.

The process 126 further includes measuring a component composition of afirst fuel, such as a process gas or a natural gas (block 130), blendingthe first fuel and a second fuel at a first ratio to create a first fuelmixture (block 132), and blending the first fuel and the second fuel ata second ratio to create a second fuel mixture (block 134). The firstfuel mixture may then be transferred to a first fuel nozzle (e.g.,primary fuel nozzle 20) of the combustor 14 (block 136), while thesecond fuel mixture may be transferred to a second fuel nozzle (e.g.,secondary fuel nozzle 22) of the combustor 14 (block 138). The blocks128, 130, 132, 134, 136, and 138 of the process 126, as illustrated inFIG. 5, may be similar to blocks 114, 116, 118, 120, 122, and 124 of theprocess 112, as illustrated and described with respect to FIG. 4.

Once the fuel mixtures of the fuel circuits are transferred to the fuelnozzles 18 of the combustor 14, the fuel may be routed by the fuelnozzles 18 into the primary and/or secondary combustion zones 52 and 54.As discussed in detail above, the primary and/or secondary zones 52 and54 of the combustor 14 may be equipped with a plurality of sensors 84,which may measure one or more operating parameters of the combustor 14(block 140). The sensors 84 may provide information on the operatingand/or combustion dynamics of the combustor 14 by taking measurements onvarious combustion dynamics parameters. For example, as described abovewith respect to FIG. 2, combustion dynamics parameters may include acombustor 14 tone frequency or amplitude, flame intensity, temperature,pressure, concentration of various components of fuel sources orcombustion products, and so forth. The sensors 84 may be any suitabletype of sensors, such as, for example, a flame detector or an acousticprobe. The sensors 84 may also be other types of sensors, such as, forexample, optical sensors, mechanical sensors, or electrical sensors, andso forth. The sensors 84 may send measured combustor 14 operatingparameter data as combustor operating feedback 88. As discussed above,the combustor operating feedback 88 may be transferred to the controller80. The memory 82 of the controller 80 may further store the measuredcombustor 14 operating parameters and data.

The controller 80 may be configured to modify fuel blending of theblending skid 74 based on the operating parameter data of the combustor14 (block 142). In this manner, the controller 80 may regulate afeedback control loop that may enable adjustment of the blending ratioof the natural gas supply 78 (e.g., natural gas) to the process gassupply 76 (e.g., process gas) within a fuel circuit of the blending skid74 based on combustor 14 operating feedback from the primary and/orsecondary combustion zones 52 and 54 or other areas of the combustor 14.For example, if the concentration of nitrogen within the first fuelcircuit 90 is outside a desired or target operating parameter of thecombustor 14, and the concentration of nitrogen within the process gassupply 76 is known or measured, the controller 80 may then adjust thethe blend ratio in subsequent blending so that it is within desirableoperating parameters. In certain embodiments, the controller 80 maycontinuously monitor the combustion dynamics of the combustor 14 for astream of real-time data. Furthermore, a stream of real-time data orfeedback may be used by the controller 80 to continuously orperiodically adjust the blend ratio of the fuel mixtures within thefirst and/or second fuel circuits 90 and 92.

Technical effects of the invention include the flexible fuel blendingsystem 50 that blends the process gas supply 76 (e.g., e.g., a blastfurnace gas, a coke oven gas, a refinery flue gas, a synthetic gasgenerated as a result of a refinery or chemical process, or acombination thereof.) with the natural gas supply 78 (e.g., natural gas)for combustion-driven operations within the gas turbine system 10. Thefuel blending system 50 may have a plurality of fuel circuits, such asthe first fuel circuit 90 and the second fuel circuit 92, and each fuelcircuit may independently have a different blend ratio of the naturalgas supply 78 to the process gas supply 76. Additionally, the first andsecond fuel circuits 90 and 92 may supply respective fuel mixtures todifferent fuel nozzles (e.g., primary fuel nozzles 20 and secondary fuelnozzles 22). Furthermore, the controller 80 may monitor the operationsof the fuel blending system 50, and may regulate blending of fuel basedon a measured composition of the process gas supply 78, a measuredcomposition of the natural gas supply 76, and/or based on real-timemonitoring of various operating parameters of the combustor 14. Thecontroller 80 may further regulate blending in a manner that achievesdesired operating parameters for the combustor 14, e.g., to maintaindesired or optimum combustion dynamics, emissions, process gasconsumption, and reduced risk, wear, or degradation to the gas turbinesystem 10.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

The invention claimed is:
 1. A system, comprising: a gas turbine enginecomprising a combustor; and a fuel blending system, comprising: a firstfuel supply configured to supply a first fuel; a second fuel supplyconfigured to supply a second fuel; a first fuel circuit configured toblend the first fuel and the second fuel to form a first fuel mixture,wherein the first fuel mixture has a first blending ratio of the firstand second fuels; a second fuel circuit configured to blend the firstfuel and the second fuel to form a second fuel mixture, wherein thesecond fuel mixture has a second blending ratio of the first and secondfuels; and a controller configured to regulate blending of the firstfuel mixture and blending of the second fuel mixture simultaneously,wherein the controller is configured to regulate blending based on ameasured operating parameter of the combustor, and wherein thecontroller is configured to simultaneously regulate the blending of thefirst blending ratio to be different from the blending of the secondblending ratio.
 2. The system of claim 1, wherein the first fuelcomprises a process gas and the second fuel comprises a natural gas,wherein the process gas comprises a coke oven gas, a blast furnace gas,a refinery flue gas, a synthetic gas generated as a result of a refineryor chemical process, or a combination thereof.
 3. The system of claim 1,wherein the controller is configured to regulate blending of the firstfuel mixture and the second fuel mixture based on a measured compositionof the first fuel and/or the second fuel.
 4. The system of claim 1,wherein the measured operating parameter comprises a combustion dynamicsparameter, a combustor tone frequency, a combustor tone amplitude, acombustor flame intensity, a pulsation or an oscillation in pressure,temperature, flame intensity, light intensity, noise, and emissionslevels, or a combination thereof.
 5. The system of claim 1, wherein thegas turbine system comprises a flame detector configured to measure aflame intensity of a flame in the combustor, and the controller isconfigured to receive feedback from the flame detector.
 6. The system ofclaim 1, wherein the fuel blending system comprises memory configured tostore the measured operating parameters of the combustor, and desiredblending ratios of the first fuel mixture and the second fuel mixture.7. The system of claim 1, wherein the first fuel circuit is configuredto supply the first fuel mixture to a primary fuel nozzle of thecombustor, and the second fuel circuit is configured to supply thesecond fuel mixture to a secondary fuel nozzle of the combustor.
 8. Thesystem of claim 1, wherein the controller is configured to regulateblending of the first fuel mixture and the second fuel mixture based ona maximum allowable concentration of nitrogen, carbon dioxide, hydrogensulfide, or oxygen in the first fuel or combustion products of thecombustor.
 9. The system of claim 1, wherein the gas turbine engine isset to a pre-mixing mode of operation, a primary mode of operation, asecondary mode of operation, a full load mode of operation, a part loadmode of operation, or a combination thereof.
 10. A system, comprising: afuel blending system, comprising: a first fuel circuit configured tosupply a first fuel mixture of a first fuel and a second fuel to aprimary fuel nozzle of a turbine combustor; a second fuel circuitconfigured to supply a second fuel mixture of the first fuel and thesecond fuel to a secondary fuel nozzle of the turbine combustor; and acontroller configured to simultaneously regulate a first blending ratioof the first fuel mixture to be different from a second blending ratioof the second fuel mixture, wherein the controller is configured tosimultaneously regulate blending of the first and second fuel mixturesbased on a measured operating parameter of the turbine combustor, andwherein the measured operating parameter comprises a chemicalcomposition of a burned first fuel mixture or a burned second fuelmixture within the combustor.
 11. The system of claim 10, wherein thefirst fuel comprises a process gas and the second fuel comprises anatural gas, wherein the process gas comprises a coke oven gas, a blastfurnace gas, a refinery flue gas, a synthetic gas generated as a resultof a refinery or chemical process, or a combination thereof.
 12. Thesystem of claim 10, wherein the measured operating parameter comprises acombustion dynamics parameter, a combustor tone frequency, a combustortone amplitude, a combustor flame intensity, a pulsation or anoscillation in pressure, temperature, flame intensity, light intensity,noise, and emissions levels, or a combination thereof.
 13. The system ofclaim 10, wherein the turbine combustor comprises at least one flamedetector configured to measure a flame intensity of a flame of thecombustor, and the controller is configured to receive feedback from theat least one flame detector.
 14. The system of claim 10, wherein thefuel blending system comprises at least one acoustic probe configured tomeasure a frequency or an amplitude of a tone of the combustor, and thecontroller is configured to receive feedback from the at least oneacoustic probe.
 15. The system of claim 10, wherein the turbinecombustor is set to a pre-mixing mode of operation, a primary mode ofoperation, a secondary mode of operation, a full load mode of operation,a part load mode of operation, or a combination thereof.
 16. A method,comprising: measuring a chemical property of an operating parameter of agas turbine combustor, wherein the chemical property of the operatingparameter is used to regulate blending of a first fuel with a secondfuel; blending, via a first fuel circuit regulated by a controller, thefirst fuel with the second fuel based on the chemical property of theoperating parameter to form a first fuel mixture having a first blendingratio; and blending, via a second fuel circuit regulated by thecontroller, the first fuel with the second fuel based on the chemicalproperty of the operating parameter to form a second fuel mixture havinga second blending ratio, wherein the controller is configured tosimultaneously regulate blending of the first and second fuel mixtures,such that the first and second blending ratios are different from oneanother.
 17. The method of claim 16, comprising supplying the first fuelmixture to a primary fuel nozzle of a turbine combustor and supplyingthe second fuel mixture to a secondary fuel nozzle of the turbinecombustor.
 18. The method of claim 16, wherein the first fuel comprisesa coke oven gas, a blast furnace gas, a refinery flue gas, a syntheticgas generated as a result of a refinery or chemical process, or acombination thereof, and the second fuel comprises a natural gas. 19.The method of claim 18, comprising maximizing an amount of the firstfuel in the first fuel mixture or the second fuel mixture based on thecomponent composition of the first fuel and the operating parameter ofthe turbine combustor.
 20. The method of claim 16, wherein measuring thechemical property of the operating parameter of the turbine combustorcomprises measuring a change in flame intensity, a change intemperature, a chemical composition of a burned fuel within the turbinecombustor, a threshold limit of nitrogen, carbon dioxide, hydrogensulfide, or oxygen within the combustion products of the turbinecombustor, or a combination thereof.
 21. The system of claim 16, whereinthe gas turbine combustor is set to a pre-mixing mode of operation, aprimary mode of operation, a secondary mode of operation, a full loadmode of operation, a part load mode of operation, or a combinationthereof.